Formal & and infomal way of saying "It's been a long time" in GERMAN
What's a formal and an informal way to say "It's been a long time (since the last time I've seen you)" in GERMAN? Smth like "long time no see"?

I found "lange nicht gesehen" ;
and "Es sit lange her" or "Es ist eine Weile her"... and they're informal of course, but is that really what Germans say amongst each other?

and what's the formal way anyway?

DANKE IM VORAUS

Question

Formal & and infomal way of saying "It's been a long time" in GERMAN
What's a formal and an informal way to say "It's been a long time (since the last time I've seen you)" in GERMAN? Smth like "long time no see"?

I found "lange nicht gesehen" ;
and "Es sit lange her" or "Es ist eine Weile her"... and they're informal of course, but is that really what Germans say amongst each other?

and what's the formal way anyway?

DANKE IM VORAUS

Answer

Informal:
Wow, wir haben uns schon so lange nicht mehr gesehen!
Lange nicht (mehr) gesehen!

Formal:
Guten Tag! Es ist schon wirklich lange her, dass wir uns das letzte Mal gesehen haben!

Answer

Nett, vielen Dank Alexej. "Ewig" ist tatsächlich ein neues Wort für mich, und wirklich nützlich!

Answer

Hey Ayoub! 
Actually you already found right expressions. 
"Lange nicht gesehen" - is for me very popular and I use it myself most of the time (and I am Austrian).
"Lange ist es her" is also common or too make it more exaggeratory "ewig nicht gesehen", "es ist Ewigkeiten her, dass wir uns gesehen haben" ....

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